1. Field of the Invention
The present invention relates to a process for producing crystalline oxytitanium phthalocyanine. More particularly, the present invention relates to a process for producing crystalline oxytitanium phthalocyanine of Type-I, which shows strong peaks in CuK.alpha. characteristic X-ray diffraction at Bragg angles 2.theta..+-.0.2.degree. of 9.0.degree., 14.2.degree., 23.9.degree., and 27.1.degree..
2. Related Background Art
Phthalocyanine pigments have recently been extensively employed as catalysts, electronic materials such as electrophotographic sensitive members, solar batteries, and sensors, as well as in conventional use in coloration of paints, inks, resins, and the like.
Various crystal structures of oxytitanium phthalocyanines are produced depending on the minute difference of production conditions as described, for example, in Japanese Laid-Open Patent Application Nos. 59-49544 (U.S. Pat. No. 4,444,861), 59-166959, 61-239248 (U.S. Pat. No. 4,728,592), 62-67094 (U.S. Pat. No. 4,664,997), 63-366, 63-116158, 63-198067, and 64-17066. The crystalline forms described in the above patent publications, however, are usually obtained as a mixture, which makes it difficult to maintain the standard quality of the products. Accordingly, a method has been desired which gives a pure crystal form of oxytitanium phthalocyanine. Many attempts have been made therefor. Processes for steady production of the A-type or C-type crystal are proposed, for example, in Japanese Laid-Open Patent Application Nos. 63-364, 63-365, 63-37163, 63-57670, and 63-80263.
Japanese Laid-Open Patent Application No. 3-128973 discloses crystalline oxytitanium phthalocyanine having strong peaks at Bragg angles 2.theta..+-.0.2.degree. of 9.0.degree., 14.2.degree., 23.9.degree., and 27.1.degree. in CuK.alpha. characteristic X-ray diffraction, namely I-type oxytitanium phthalocyanine, and a process for production thereof. However, there is still a need to produce a crystal having higher purity by using a simpler process.
When crystalline oxytitanium phthalocyanine is used as an electric charge-generating substance, the electrophotographic properties of the resulting photosensitive member may delicately vary depending on production conditions.